Glaucoma is a blinding eye disorder characterized by a defect in the outflow of aqueous humor, elevated intraocular pressure, and visual field loss. Although the trabecular meshwork is the major route for aqueous outflow, the cells of this structure have proven difficult to evaluate because of limitations on trabecular tissue available for study. For this reason, we have explored the propagation of human trabecular cells in tissue culture. Over the past three years, we have evaluated a number of human trabecular cell lines which appeared to maintain their initial rate of cell division and the differentiated morphology of uncultured trabecular tissue, after serial passage in culture. In the proposed studies we will employ cultured human trabecular cells (1) to define improved conditions for cell growth and (2) to examine important physiological and phathological responses of the trabecular cells. quantitative assessment of cell division and detailed electron microscopic observations of the different trabecular cell lines will be employed in these studies. The use of well-defined trabecular cell material will permit direct evaluations of the effects of exogenously added materials (including phagocytosed substances, drugs which alter cellular architecture, specific growth factors, etc.) on trabecular cell structure and function. In addition, studies designed to evaluate the biochemical specificity of trabecular cells (including cellular and cell surface proteins, and extracellular collagen, glycoproteins glycosaminoglycans, etc.) may further add to our understanding of the functional role of trabecular cells inthe maintenance of aqueous outflow. By comparing the information obtained from the cultured trabecular cells to that obtained from excised human trabecular tissue, we hope to better understand the prospects and limitations of the cultured trabecular cell system for glaucoma research.